Take this with a grain of salt as I only sing a bit of backup and can only sing and play a couple songs, but the best advice that I think I’ve heard on the topic is that it’s not about learning to do two things at once, it’s learning the single act of playing and singing. In other words, you are learning to use your hands and voice to perform one thing. I’ve heard the advice about learning each individual thing until you can do it in your sleep, put it on autopilot, and then do both. But I think it has more to do with working out how the two things mesh and getting comfortable with it. I hope that makes some sense, I think it’s helped me to do what I’ve been able to do.
